Synthesis of base oils and fuels from fatty acids

Abstract

Processes and systems for producing base oils and fuels from fatty acids comprising, in an embodiment, oligomerizing at least one unsaturated fatty acid to provide a mixture of fatty acid oligomers, wherein the mixture of fatty acid oligomers comprises fatty acid trimers and heavier molecules; and hydrotreating the mixture of fatty acid oligomers to provide a product comprising hydrotreated fatty acid oligomers including hydrotreated trimers and heavier molecules, wherein the product has a pour point and other characteristics suitable for use as a base oil, and wherein such processes for base oil production do not require an isomerization step.

What is claimed is: 
     
         1 . A process for base oil production, comprising:
 a) oligomerizing at least one unsaturated fatty acid to provide an oligomerization product comprising a mixture of fatty acid oligomers; and   b) hydrotreating at least a portion of the oligomerization product to provide a base oil product having a pour point less than −12° C., wherein the process does not include a step for isomerizing the oligomerization product.   
     
     
         2 . The process according to  claim 1 , wherein the base oil product has a pour point less than −18° C. 
     
     
         3 . The process according to  claim 1 , wherein the base oil product comprises at least 10 wt % hydrotreated fatty acid trimers and heavier molecules. 
     
     
         4 . The process according to  claim 1 , wherein:
 step a) comprises contacting the at least one unsaturated fatty acid with an oligomerization catalyst in the presence of water in an oligomerization zone under oligomerization conditions to provide the mixture of fatty acid oligomers; and   step b) comprises contacting the mixture of fatty acid oligomers with a hydrotreating catalyst in the presence of hydrogen gas in a hydrotreating zone under hydrotreating conditions to provide the base oil product.   
     
     
         5 . The process according to  claim 4 , wherein:
 the oligomerization conditions comprise a temperature in the range from 400 to 500° F., a pressure in the range from 0 to 500 psig, and a LHSV in the range from 0.05 to 1.0 hr −1 , and   the oligomerization catalyst comprises an acidic clay catalyst.   
     
     
         6 . The process according to  claim 4 , wherein:
 the oligomerization zone is separate from the hydrotreating zone, and   step a) is performed in the absence of hydrogen pressure.   
     
     
         7 . The process according to  claim 1 , wherein the oligomerization product further comprises unconverted fatty acids monomers, and the process further comprises:
 c) separating the unconverted fatty acids from the mixture of fatty acid oligomers, and wherein step b) comprises hydrotreating the mixture of fatty acid oligomers after step c).   
     
     
         8 . The process according to  claim 1 , wherein the base oil product has a kinematic viscosity at 100° C. in the range from 4 to 10 cSt. 
     
     
         9 . The process according to  claim 1 , wherein the base oil product constituents have an average molecular weight in the range from 400 to 800. 
     
     
         10 . The process according to  claim 1 , wherein the base oil product has a Viscosity Index in the range from 120 to 150. 
     
     
         11 . The process according to  claim 1 , wherein the base oil product has an NMR branching index in the range from 10 to 30. 
     
     
         12 . The process according to  claim 1 , wherein the base oil product has an average degree of molecular branching in the range from 2 to 4 alkyl branches per 100 carbon atoms. 
     
     
         13 . A process for base oil production, comprising:
 a) contacting a fatty acid feed comprising at least one unsaturated fatty acid with an oligomerization catalyst in an oligomerization zone under oligomerization conditions to provide a mixture of fatty acid oligomers; and   b) contacting the mixture of fatty acid oligomers with a hydrotreating catalyst in a hydrotreating zone under hydrotreating conditions to provide a base oil product having a pour point less than −12° C., wherein the process is performed in the absence of an isomerization step.   
     
     
         14 . The process according to  claim 13 , wherein:
 the oligomerization conditions comprise a temperature in the range from 400 to 500° F., a pressure in the range from 0 to 500 psig, and a LHSV in the range from 0.05 to 1.0 hr −1 ,   step a) is performed in the absence of hydrogen pressure, and   the fatty acid feed comprises from 0.5 to 3.0 wt % water.   
     
     
         15 . The process according to  claim 13 , wherein the base oil product has a kinematic viscosity at 100° C. in the range from 4 to 10 cSt, a Viscosity Index in the range from 120 to 150, an NMR branching index in the range from 10 to 30, and an average degree of molecular branching in the range from 2 to 4 alkyl branches per 100 carbon atoms. 
     
     
         16 . The process according to  claim 13 , wherein:
 the fatty acid feed comprises at least 90 wt % C 16 -C 20  free fatty acids, and   at least 20 wt % of the base oil product boils at a temperature above 900° F.   
     
     
         17 . A process for base oil production, comprising:
 a) oligomerizing at least one unsaturated free fatty acid to provide an oligomerization product comprising a mixture of fatty acid oligomers, wherein the mixture of fatty acid oligomers comprises fatty acid trimers and heavier molecules; and   b) hydrotreating the mixture of fatty acid oligomers to provide a base oil product, wherein:   the base oil product comprises hydrotreated fatty acid trimers and heavier molecules,   the hydrotreated fatty acid trimers and heavier molecules jointly represent from 15 to 20 wt % of the base oil product, and   the base oil product has a pour point less than −12° C.   
     
     
         18 . The process according to  claim 17 , wherein the base oil product is obtained in the absence of an isomerization step. 
     
     
         19 . The process according to  claim 17 , wherein:
 the at least one unsaturated free fatty acid is selected from a C 12  to C 22  fatty acid,   step a) comprises contacting the at least one unsaturated free fatty acid with an oligomerization catalyst in an oligomerization zone under oligomerization conditions in the absence of hydrogen pressure to provide the mixture of fatty acid oligomers,   the oligomerization catalyst comprises an acidic clay catalyst,   the oligomerization conditions comprise an oligomerization temperature in the range from 400 to 500° F., and   the base oil product constituents have an average molecular weight in the range from 400 to 800.   
     
     
         20 . The process according to  claim 19 , wherein the base oil product, as provided by step b) and in the absence of an isomerization step, has a kinematic viscosity at 100° C. in the range from 4 to 10 cSt, a Viscosity Index in the range from 120 to 150, and a pour point less than −18° C.